TB993tt

Following my sarcasm to Colin at 9M for promoting his untested intercooler for the 993tt he stepped up and supplied Phelix with the “9M Prototype” intercooler for us to test on our airstrip day…

The history of aftermarket intercoolers for the 993tt is littered with failures with every manufacturer claiming that their product flows the best and cools the best but never with any hard scientific test data to support their guesswork. The TTP “V Flow” intercooler was sold in large numbers through companies like FVD and Cargraphic it was indeed 50% larger than stock and had a fancy “V” flow bit on the back – but the only test I ever saw was one I did which was only at low speed and the “V Flow” failed miserably – it was worse than stock.

RS Tuning tried and failed to produce a better than stock intercooler (I saw the evidence at their workshop, a shelf full of “prototypes”) and the only options they would use was the stock unit for applications up to around 550hp and the Secan EVO Porsche Motorsport unit for 550+hp. As we know the Secan EVO unit now costs over $30K

The 993tt using Motronic M5.2 has assisted the vendors of aftermarket intercoolers since because of its advanced knock control when the inlet air gets too hot the Motronic will in stages protect the engine starting at 37.5 Degrees Centingrade where the timing is pulled by 0.5degrees and by 70.5 DegC the timing is pulled by 6 degrees with an accompanying reduction in boost pressure (see chart below which is for my engine done by RS Tuning so numbers may vary on a stock engine but you get the gist)



If the intake temperature gets too high the Motronic can just kill the spark. So the 993tt engine will “put up with” any intercooler which the poor old consumer decides he likes the look of and the only way to test it is to do a back to back test against the stock one. Amazingly one never hears of any manufacturer actually doing these tests, some quote numbers in terms of “efficiency” and of course relative size and of course the ubiquitous “flow rate” which on paper looks great and makes sense, but all we really want to know is how cool the intake temperature is (if the bloody thing doesn’t flow well enough then this will be reflected in hotter intake temp).

Intercoolers used for racing certainly have a harder time than street driving since the air flow over them is constantly varying being interrupted as the car slows for corners, this is one reason why RS Tuning engines are relatively conservatively mapped as they are all mapped to their “race” standard so they inherently do not get very hot and can keep producing power under race conditions (within the scope of the intercooler used)

The test is basically running the car up to 180mph at which point the engine is at full load for a number of seconds and the intercooler has maximum airflow through it – What I find amazing is that the intake temperature actually stabilises and doesn’t continue rising, this is good for the test but I suspect that under different conditions (like racing or aggressive street driving) the inlet temperature will indeed get quite a lot higher than during this “full load” test.

The engine used is MOD500s engine which is built to an RS Tuning specification using RSK24/26 turbos (which have been further improved by UMW featuring zero clearance) RS hydraulic cams, big exhaust, EVO head sealing and fully mapped on the engine dyno by RS Tuning to deliver a peak power of 533PS DIN.
This car wearing its Secan and weighing ~1630kg does 0-300kph in ~36s (about the same as a 997GT2)

For the test we simply read the Intake Air Temperature (IAT) from the diagnostic port which is the information the ECU sees and reacts to. I am uploading a video of the test – it is boring but gives you the detail of how we did it.

The different intercoolers were all tried on Mods car. The contenders were:

Secan by RS Tuning cost approx $16K
Stock by Porsche cost free
9M Prototype cost TBA

Here are pictures of the units side by side black one is stock followed by 9M followed by Secan. The Secan is fatter and has 3 more channels (total 18) running down it.





The results

The ambient temperature for the stock test was around 18DegC and the maximum stable full load intake temp was 54DegC

The ambient temperature for the Secan test was around 16DegC and the maximum stable full load intake temp was 33 DegC

The ambient temperature for the 9M Prototype was 17DegC and the maximum stable full load intake temperature was 42DegC

I have to admit that MOD and I were slightly relieved that our seemingly reckless purchase of our Secan units was validated in this test but were also impressed that 9M Prototype did deliver the goods.

If you refer back to my data at the top you will see that during our test on the stock car at 54DegC the Motronic will be pulling the timing by 4.5degrees (with a small boost pull also) but on the 9M Prototype equipped run the timing pull will only be 0.5degrees – this is very significant and is free horsepower with zero added stress on the engine. The actual value of the “free” horsepower on MODs 533hp car would be around 20-30hp (I know this since I know the Motronic reverts to 52.5DegC setting when the intercooler temp sensor is unplugged and RS told me this costs you these sorts of numbers compared to optimum timing )
So 9M can accurately claim that their Prototype 993tt intercooler “can” be a “bolt on” 30hp – Congratulations to Colin and I apologise for my initial scepticism, technology has moved on.

As ambient temperatures increase it becomes even harder for the intercooler to do its job since every heat producing part of the car has warmer cooling air running over it resulting it much hotter post turbo pre intercooler air temperatures -This is where RS Tuning claim that their Secan really performs, on 30+DegC days - how the 9M one does is open to conjecture but it would seem likely that it would still be substantially better than stock but exactly how much timing and hp you would win is for another test and another day

Disclaimer
Myself MOD Phelix have not recieved any payment of any kind from 9M, this was0 purely for fun and for knowledge - having said that MOD and Phelix spent so much time swapping intercoolers that they both only got through half a tank of fuel (compared to my full tank as I did 25+ runs) So if Colin decided to give Phelix the Prototype for a very substantial discount it would be fair compensation for the costs and time involved - IMO

LAT

Good work everyone and thanks for reporting, this is the kind of information too often lacking from performance claims.

On the topic of IC units, Toby I believe I sent you pictures of the IC on my car with the RS Tuning motor. Were you able to establish if it is a OEM motorsport unit or just a one off, is there anything I can look for to identify the unit?

How do the OEM motorsport units compare in price and performance to the stock and the Secan?

I am still not home but have covered 3,000 Km of my 3,500 km journey home. BTW it is a total Wow car although I have no data yet. I can say I will not miss my 997TT.

I am supposed to hook up with Woodster today so there may be a chance to quantify some play otherwise next week.

Geoffrey

Interesting test Toby. A few obversations about data collection. I think that it would have been interesting to also note the cylinder head temp and oil temp at the beginning of each run since they are the primary indicators of engine temperature and can greatly influence cooling ability as they heat soak.

Second, although the last run was started with only a 1 degree ambient temp difference, that 1 degree follows the cooling ability all through the run. It isn't a matter of saying the ending temp is 42 - 1 = 41 degrees to compensate for the increased ambient temp. I think it might be more than that.

In any case, interesting data, thanks for sharing.

sfbanchs

Dam Toby as per your advice i sold my 9m unit a year ago and went back to stock

Felix

Not possible me thinks - you sold a cargraphic unit if I recall correctly?

sfbanchs

yes it was cargraphic isn't it from the same manuacturer though?

TB993tt

LAT, your intercooler is definately the OEM Porsche motorsports pre EVO model. RS Tuning told me that they were good to support ~550hp about the same as stock...... without testing side by side it would be hard to guess whether they were right or wrong but you would think that Porsche knew what they were doing to some extent and that it would be more efficient than stock wouldn't you ?

Really looking forward to hearing lots about your new car

Geoffrey
Yes we were discussing the effect of the varying ambient temperature and how like you say there is not a linear relationship between say 1degC ambient increase and 1 degC intake increase - this is why I attempted to show the increasing ambient although we were guessing at it a bit since our in car gauges were reading all over the place !

You are right, we should have read off the relative cylinder head temperatures, it would have been easy - forgot in the excitement

sfbanchs
The intercooler you ditched was the one I referred to at the begining they were made by TTP - pile of junk

WHB Porsche

No, I think Cargraphic was the same as FVD. The 9m unit is new.

How was the fitment of the 9m piece? Was it truly a bolt-on part? The 993tt intercooler is one of the trickiest out there considering its mounting to the throttle body.

Felix

Fitted perfectly; like many aftermarket ICs it uses the center and ends from a stock intercooler.

graeme36s

Hats off to you all for a very interesting post and for taking the time out to swap the i'cs around. Top men. Sorry I could not make it this time, hopefully next, reards Graeme

sfbanchs

thanks for the clarification, where can i get this 9m intercooler put me on the list

Jussi

Why this new 9M IC is same size as stock IC, wouldn't it be more efficient if it had been similar than Secan IC from it's dimensions.. ?

I think that stock IC size is too restrictive for bigger airflow.. makes too much heat..

Put those "3 missing channels" for it and I'll buy one

LAT

I measured my intercooler cells and they have 25 channels and are 38.5 cm by 26.0 by 6.0 cm thick each from tank to center.

Do you have the sizing on the ones you tested?

MOD500

What a great day, so much fun Much thanks to Phelix for organising the micro v-max

Was quite a privilege to be involved with the intercooler testing ... was very exciting hearing the IAT numbers called out as the Banana flew down the runway onwards to 180 mph plus.

Could the chaps with other makes of aftermarket intercoolers do some testing .... just need to get hold of a Hammer and a mile straight track. Would be great to get some knowledge on other units

Edited to say .... hopefully to going a Pistonheads v-max day next month, hopefully it will be red hot and will get some data on the Secan again, would gladly test the 9M unit back to back with pleasure. A video of last summer's Secan testing, video courtesy of Ruxpin .... wear your Anoraks with pride Gentlemen:

http://video.google.co.uk/videosearc...en&sitesearch=

Jean

Thanks again for the interesting reading. The learnings from the datalogged runs are outstanding, namely how boost is pulled back with temperature and resulting impact on performance, much more can be learnt once we draw the Hp and torque curves for every run..

In line with what TB mentioned, I think that one needs to be aware that you get exponential fresh airflow as speed increases, bigger and thicker cores do a better job at keeping the temps down in presence of strong airflow, and the opposite is true as well, a thinner core does a better cooling job at lower speeds, such as on the track, since the amount of hot air inside the cores takes less time to be evacuated. If the Secan holds the temperature differential within 25deg C of ambient temps in a race environment, this would translate into immense gains over the duration of a sprint race, let alone an endurance race. No wonder these cores are so expensive, the alloys used and R&D that go behind building them make the difference between winning or loosing a race.

For street usage, I think one is ok with the stock cooler, if you look at the temperature differential up to 4th. gear at WOT, the difference in temperature is not that large.

Thanks again guys.